Staff MemberModerator

Highly interesting ... I had no idea torpedos were actively roll-stabilized in flight. Do you know whether this was a peculiarity of the German torpedos, or if other torpedos had it too?

Regards,

Henning (HoHun)

Click to expand...

Hi Henning, off hand I do not remember. I was not able to read the documents posted above because I can't read German I just understand enough of it to be dangerous.

Below is a link to japanese torpedo's in english. Ive read them a while back but dont remeber if they where actively roll stabilized or not. Some where around here I have some more torpedo manuals provided to me by a friend written in other languages but I only know one lauguage, English. Kinda restricts my research because it takes me so long to translate.

"There were no remarkable features about Japanese torpedoes in operational use during the war, with the exception of the anti-roll stabilizers. The Japanese considered this innovation of great importance in improving torpedo performance."

Apparently, a torpedo not roll-stabilized would tend to hit the water rolled off the upright position, and since the torpedo body would be nose-down, the water elevator would already be in "nose up" deflection and induce a sharp "hook" as soon as the torpedo hit the water.

While running submerged, roll control was also important since it eliminated the requirement to keep the torpedo laterally stable statically, which could only be done by leaving an air bubble in its upper half, restricting space available for equipment and warhead. (Apparently, this layout was used in the early model torpedos, and introduction of roll stabilization allowed the use of larger warheads within the same outer dimensions later.)

From the emphasis in the summary, it sounds a bit as if US torpedoes did not use anti-roll stabilization ... it would have hardly been considered a "remarkable feature" if it would have been in common use in US torpedoes, too.

The Japanese actually pioneered the use of anti-roll flippers with their Type 91 aerial torpedo starting with the Mod 2, and was used on all subsequent Mods thereafter. This innovative feature required an extra gyro to stabilize it, and was in fact used in the Pearl Harbor attack. One was dredged from the harbor in remarkably fantastic condition considering its age, circa 1991. Because the warhead was 'sweating' its explosive, a decision was made to detonate it with a shape charge. Anyway, the rear section is on display at the Pearl Harbor Museum.
The Germans were very interested in Japanese torpedo technology, and I am given to understand that Japan (probably Germany, too) visited one another via submarine numerous times. Japan in turn received info on Germany's ME-262 and ME-163 fighter aircraft (Japan's K9Y 'Kikka' and J8M 'Shusui', respectively).

Attached Files:

Italian Torpedoes too had stabilizers but for the flight phase of the torpedo run. These stabilizers were studied for long time and where put in service in 1942.
The photo shows such solution on a SM 79 mounted torpedo

Hi HoHun,
you are completely right. Stabilizers showed in the photo detached from the torpedo at its impact with water. Their sole scope was to control that, during the air phase, the torpedo axis would be tangent to the (almost) parabolic path of its center of mass. This to insure the optimal torpedo to water impact angle that had to be in the range 15°-30°. During the flight there could be a small alti-roll stabilizing action but as for the anti-pitch action, no closed loop control system was implemented. Just ground setting for the movable part of the stabilizer. That is a coarse pre compensation if transversal wind was predictable. But it was a clearly problematic prediction.
Pre-war studies (1939) show that italian developers were aware of the negative impact of the in flight roll disturbances, on the marine trajectory of the torpedo and that the only way to effectively "fight" this problem was to adopt gyro-controlled devices but, in spite of it, italian torpedo were never equipped with such devices.

Hi Microdow,
thanks for the link ,-). I had dowloaded it on october 12th. I can tell you it was quite interesting to read since it is closely in line with italian written documents on the subject.

Maybe it is useful to know that the "circling torpedo" was developed "against" the "big shots" opinion. So all was done with minimum fundings and the practical results where, obviously, poor. The basic idea was quite good (as HoHun noticed) but the lack of money and manpower prevented it to become an effective weapon.

This may have been asked and answered, but does anyone know what the color(s) of the german torpedos used by E-Boats was? I'm in the process of building an S-100 type E-Boat and want to get the color of the spare torpedos correct.

(1) Did the IJN at any stage in the war share with the Germans the secret of their oxygen drinven type 93 and 95 torpedoes?

(2) Does any expert here believe that it is possible to fire two small torpedoes, or two full-bore but short length torpedoes, from one large torpedo tube?

Click to expand...

HI, #1 i am not sure if they shared any information to Germany but, if you are interested i have a post war report from the USA, that describes the torpedo in great detail.

#2 I don't believe it was possible as the impulse air was ejected from the rear on the torpedo tube, if there was "two small torpedoes" i am going to assume you meant small diameter torpedoes, i believe they would not work as the air pressure would be dissipated from the tube by the gaps in the tube. But it may be possible if there was some sort of gasket. But if you try to fire 2 two full-bore but short length torpedoes you run the risk of damaging the warhead and the propellers of the torpedo.

Lastly the idea was to fire torpedoes in a spread one in front of the target, one to hit the middle and one behind, in case there was a mistake in the targets speed or course.

PS. do you current live in Burma, i ask because i have a friends from there who say it is very terrible over there.

I still think, however, that 2 full-bore but short torpedoes could have been fired from a single tube, if there was a washer separating them. This solution is similar to some solutions in artillery, BTW.

As for your last question, some things are best discussed privately through...oh, let's say...that thingy called a "PM".

HI, if it was possible by using a washer separating the torpedoes. There comes the issue of why, it would be much more efficient to use multiple tubes. Then you could shoot as all or just one at a target. There is also the issue of cost torpedo's are very expansive and to waste 2 of them on the same course would just be throwing money away. This is a little off topic but i attached some drawings of torpedo tubes from the early 1890s. Tom

Well, I was thinking that the japanese oxygen torpedoes were much more efficient than the G7. I did a rough paper excercise and found you could design a torpedo with oxygen propulsion that would be 21 inches, 150 inches long, about 36 knots, 770 lb warhead, 2000 meter range.

And it would weigh about 2000 - 2200 lbs.

Now that is just about half the weight and length of the G7.

So without having to design a whole new submarine, you could double the torpedo storage of the Type VII sub.

And...with two in one tube...you could expose yourself deliberately to a destroyer...and as it ran at you, fire at it with eight fish. A guaranteed kill if it was a "down the throat" shot.

Let's take the oxygen/kerosene japanese type 2 special 1942 model. It was a 45 cm (17.7 inch , or let's say 18 inch torpedo) with a length of 5.6 m or 221 inches. It weighed 975 kg - 2140 lbs - with a warhead of 770 lb, equal to the warhead of the standard german 21 inch torpedo. It had a speed of 38 to 40 knots and a range of 2000 meters.

Now lets fatten this torpedo to 21 inches while shortening its length. Using a cubic volume equation, we arrive at a length of 67% of the 220 inches, or about 150 inches. Since the standard 21 inch torpedo (the G7a ) of the KM in WW II had a length of 283 inches, the possibility of using two torpedoes in one tube is looking quite plausible from a space point of view!